LLSQ Class Reference

#include <linlsq.h>

Public Member Functions
	LLSQ ()
void	clear ()
void	add (double x, double y)
void	add (double x, double y, double weight)
void	add (const LLSQ &other)
void	remove (double x, double y)
inT32	count () const
double	m () const
double	c (double m) const
double	rms (double m, double c) const
double	pearson () const
FCOORD	mean_point () const
double	rms_orth (const FCOORD &dir) const
FCOORD	vector_fit () const
double	covariance () const
double	x_variance () const
double	y_variance () const

Detailed Description

Definition at line 26 of file linlsq.h.

Constructor & Destructor Documentation

LLSQ()

LLSQ::LLSQ ( )

inline

Definition at line 28 of file linlsq.h.

         {  // constructor
    clear();  // set to zeros
  }

Member Function Documentation

add() [1/3]

void LLSQ::add	(	double	x,
		double	y
	)

Definition at line 49 of file linlsq.cpp.

                                 {          // add an element
  total_weight++;                           // count elements
  sigx += x;                     // update accumulators
  sigy += y;
  sigxx += x * x;
  sigxy += x * y;
  sigyy += y * y;
}

add() [2/3]

void LLSQ::add	(	double	x,
		double	y,
		double	weight
	)

Definition at line 58 of file linlsq.cpp.

                                                {
  total_weight += weight;
  sigx += x * weight;                     // update accumulators
  sigy += y * weight;
  sigxx += x * x * weight;
  sigxy += x * y * weight;
  sigyy += y * y * weight;
}

add() [3/3]

void LLSQ::add

(

const LLSQ &

other

)

Definition at line 67 of file linlsq.cpp.

                                {
  total_weight += other.total_weight;
  sigx += other.sigx;                     // update accumulators
  sigy += other.sigy;
  sigxx += other.sigxx;
  sigxy += other.sigxy;
  sigyy += other.sigyy;
}

c()

double LLSQ::c

(

double

m

)

const

Definition at line 117 of file linlsq.cpp.

                             {          // get constant
  if (total_weight > 0.0)
    return (sigy - m * sigx) / total_weight;
  else
    return 0;                    // too little
}

clear()

void LLSQ::clear

(

)

Definition at line 33 of file linlsq.cpp.

                 {  // initialize
  total_weight = 0.0;                         // no elements
  sigx = 0.0;                      // update accumulators
  sigy = 0.0;
  sigxx = 0.0;
  sigxy = 0.0;
  sigyy = 0.0;
}

count()

inT32 LLSQ::count ( ) const

inline

Definition at line 41 of file linlsq.h.

                      {  // no of elements
    return static_cast<int>(total_weight + 0.5);
  }

covariance()

double LLSQ::covariance ( ) const

inline

Definition at line 73 of file linlsq.h.

                            {
    if (total_weight > 0.0)
      return (sigxy - sigx * sigy / total_weight) / total_weight;
    else
      return 0.0;
  }

m()

double LLSQ::m

(

)

const

Definition at line 101 of file linlsq.cpp.

                     {  // get gradient
  double covar = covariance();
  double x_var = x_variance();
  if (x_var != 0.0)
    return covar / x_var;
  else
    return 0.0;                    // too little
}

mean_point()

FCOORD LLSQ::mean_point

(

)

const

Definition at line 167 of file linlsq.cpp.

                              {
  if (total_weight > 0.0) {
    return FCOORD(sigx / total_weight, sigy / total_weight);
  } else {
    return FCOORD(0.0f, 0.0f);
  }
}

pearson()

double LLSQ::pearson

(

)

const

Definition at line 154 of file linlsq.cpp.

                           {  // get correlation
  double r = 0.0;                  // Correlation is 0 if insufficent data.

  double covar = covariance();
  if (covar != 0.0) {
    double var_product = x_variance()  * y_variance();
    if (var_product > 0.0)
      r = covar / sqrt(var_product);
  }
  return r;
}

remove()

void LLSQ::remove	(	double	x,
		double	y
	)

Definition at line 83 of file linlsq.cpp.

                                    {          // delete an element
  if (total_weight <= 0.0)                       // illegal
    EMPTY_LLSQ.error("LLSQ::remove", ABORT, NULL);
  total_weight--;                           // count elements
  sigx -= x;                     // update accumulators
  sigy -= y;
  sigxx -= x * x;
  sigxy -= x * y;
  sigyy -= y * y;
}

rms()

double LLSQ::rms	(	double	m,
		double	c
	)		const

Definition at line 131 of file linlsq.cpp.

                                          {          // get error
  double error;                  // total error

  if (total_weight > 0) {
    error = sigyy + m * (m * sigxx + 2 * (c * sigx - sigxy)) + c *
            (total_weight * c - 2 * sigy);
    if (error >= 0)
      error = sqrt(error / total_weight);  // sqrt of mean
    else
      error = 0;
  } else {
    error = 0;                   // too little
  }
  return error;
}

rms_orth()

double LLSQ::rms_orth

(

const FCOORD &

dir

)

const

Definition at line 196 of file linlsq.cpp.

                                             {
  FCOORD v = !dir;
  v.normalise();
  return sqrt(v.x() * v.x() * x_variance() +
              2 * v.x() * v.y() * covariance() +
              v.y() * v.y() * y_variance());
}

vector_fit()

FCOORD LLSQ::vector_fit

(

)

const

Definition at line 252 of file linlsq.cpp.

                              {
  double x_var = x_variance();
  double y_var = y_variance();
  double covar = covariance();
  double theta = 0.5 * atan2(2.0 * covar, x_var - y_var);
  FCOORD result(cos(theta), sin(theta));
  return result;
}

x_variance()

double LLSQ::x_variance ( ) const

inline

Definition at line 79 of file linlsq.h.

                            {
    if (total_weight > 0.0)
      return (sigxx - sigx * sigx / total_weight) / total_weight;
    else
      return 0.0;
  }

y_variance()

double LLSQ::y_variance ( ) const

inline

Definition at line 85 of file linlsq.h.

                            {
    if (total_weight > 0.0)
      return (sigyy - sigy * sigy / total_weight) / total_weight;
    else
      return 0.0;
  }

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The documentation for this class was generated from the following files:

• ccstruct/linlsq.h
• ccstruct/linlsq.cpp